Prior to 2016 there were two versions of the spreadsheet for each class.

In each case (M, 10R and A Class) the version available to the public (for use by official measurers, designers, sail makers and owners) allowed for data entry and calculation only and could not produce a certificate. The version made available to the IRSA DNMs only for use by their certification authority could produce a certificate. The idea was that it would be impossible forofficial measurers or others to have access to the certificate creation page.

In practice this did not work and the certificate creation versions were openly available. Recognising the way these things work in real life led the IRSA TC and EC to the conclusion that only one version of the spreadsheets is needed as it is the signature and official stamp on a certificate that authenticates it rather than the software from which it is produced.

Certification authorities are advised to take care to ensure that the method of signing and attaching their official stamp does not lend itself to illicit copying.

Each spreadsheet contains a (hidden) algorithm that finds a two digit code that is printed on each sheet of a certificate. The same code will be created each time the same data is entered. This is a simple precaution that confirms that the 'certificate' has been produced on the official IRSA version of the spreadsheet.